Hello, I live in Fl, and know it is very hot driving in 92-94F weather. I recently got this car. When I am finished with a drive in the heat the temp. goes to the L of normal. In the evening it is right in the center of normal. When I shut the car down, after about a minute the car starts percolating and losing some water. The fans are working , the water pump and thermostats appear to work. I feel like I am on the edge of overheating. I was thinking of replacing the 13 psi cap with a 15, and increasing the antifreeze mix to up the boiling point of the fluid. Any advice?? Thanks very much.

David

Submitted by david42581@yahoo.com on Sun, 08/03/2008 - 13:28

Well, bit the bullet and bought and installed a Ron Davis aluminum radiator, went in beautiful. Took the car out yesterday, the ambient temperature was about 95F. This car is running cool. Checked the car after the highway drive with an IR thermometer, it was running 199!! This was vs 240F. Thanks for the great advice!!

David

Submitted by bonnettoboot@e… on Fri, 06/20/2008 - 22:15

David, although the XJ versions of the 12 Cyl cars were noted for overheating this was not the case with the E types. The E layout was much cleaner which permitted better air flow over the engine, it also had balanced air flow from the twin fans. My first option would be to remove and test the thermostats, then install 74 deg units as opposed to 88 deg. One of the original design problems was the fitting of only one temp gauge on the right bank, if the left bank thermostat malfunctioned, there was no indication of it. In those days we often fitted an additional gauge on the left side. Your car is almost 35 years old and it may be difficult to trace its service history. If all is working properly the fans should come on between the R & M and keep the reading there, most fans are original and are likely providing substantially less air flow than when they were new. A have a very high opinion of the V12E.

Submitted by NE52-32043 on Fri, 06/20/2008 - 16:00

David,

First of all, congrats on the new car. Overheating issues are fairly common in the V12 cars, but can be controlled in a few ways.

First of all, the best mixture to run is 50/50 Prestone (or similar good coolant) and distilled water, with a bottle of Red Line Water Wetter added. Water Wetter helps with overall cooling.

Next, check your hoses, especially the lower hose that runs from the bottom of the radiator to the water pump. That is an oft-forgotten hose, even when the top hoses are changed. If that lower hose is soft when you squeeze it, change it. The suction from the water pump is strong enough to cause that hose to collapse, restricting the flow of water through the system while you are driving. A new length of good, rigid hose will solve that problem.

Also, check the thermostats (one on each side) and make sure that they are in good condition and properly installed. Some mechanics will replace these with the wrong type, so be sure they are correct for your car and have the "jiggle" valve on them installed at 12 o'clock to be sure that air is properly bled from the system.

When I had a Ser. III E-type, and an '89 XJS V12 as well, I would sometimes hear the "boiling" inside the engine after shutdown. I found that went away when I had everything else working right. Don't go to a 15 psi cap; you'll increase internal pressures too much and blow a hose.

Don't focus on the gauge. L in Normal is fine. R-M is good, but L is not that high that you have to worry. If you are concerned about the engine temps, use an infrared thermometer to check the actual temperature of the engine water manifolds and radiator.

Oh, one last possible solution, which I did on my Ser. III XKE -- an aluminum radiator or recore existing radiator with a high efficiency core. I installed a Ron Davis aluminum radiator, and the car ran consistently cool (mid-normal), even in the worst heat of summer.

Since you mentioned that the fans are working, I'm skipping those and the otter switch, but one other alternative is to install modern fans that move a lot more air than the originals.

Hope that helps.

Steve